Oil mist lubricating method



Nov. 8, 1960 K. E. A. GOTHBERG ETAL 2,959,249

- 011. Mm LUBRICATING METHOD Original Filed MarchG, 1947 5 Sheets-Sheet1 j 6 F|G..1. 35 v v INVENTORS VW gin 0% 1 Nov. 8, 1960 K. E. A.GOTHB-ERG mm. 2,959,249

OIL MIST LUBRICATING METHOD Original Filed March a, 1947 s Sheets-Sheet2 a v rd 6 IWWNW I.- v i v INVENTORS KARL EVALD ANDREAS GOTHBERG SIGURDSANDAHL BY THEIR ATTORNEYS K. E. A. GOTHBERG ETAL OIL MIST LUBRICATINGMETHOD Original Filed March 6, 1947 Nov. 8, 1960 3 Sheets-Sheet 3 SIGURDSANDAHL BY THEIR ATTORNEYS im afi f United States Patent OIL MISTLUBRICATING METHOD Karl Evald Andreas Gothberg, Backasen Lerum, andSigurd Sandahl, Heden, Billdal, Sweden, assignors to AktiebolagetSvenska Kullagerfabriken, Goteborg, Sweden Continuation of applicationSer. No. 336,162, Feb. 10, 1953, which is .a division of applicationSer. No. 732,901, Mar. 6, 1947. This application Oct. 23, 1957, Ser. No.694,060

2 Claims. (Cl. 184-7) Our invention relates generally to methods oflubrication, and more particularly to a novel method for conveying oilfrom a central source in the form of a mist, and precipitating oil fromthe mist near the bearing to be lubricated.

This application is a continuation of our copending application, SerialNo. 336,162, filed February 10, 1953, now abandoned, which latterapplication is a division of our application Serial No. 732,901, filedMarch 6, 1947, which matured into Patent No. 2,642,156 on June 16, 1953.

It has been proposed to lubricate bearings with oil mist generated in anoil mist lubricator, which supplies oil mist to one or more bearings.This system has several advantages as compared to other lubricatingsystems; for instance, lubrication with drip oilers or the like. Oneadvantage is that the oil consumption can be greatly reduced, since therate at which oil is supplied to the bearings can be considerablydiminished without the risk of interruption of the supply of oil to anyof the bearings.

Although the saving is considerable as compared with other lubricatingmethods, much oil is still lost because of the oil supplied to a bearingas oil mist, usually less than 0.5 cm. per hour, quite a largeproportion escapes through the bearing seals to the atmosphere.

The purpose of the present invention is further to reduce the oilconsumption in lubricating systems with oil mist lubricators, and ischaracterized mainly by one or more local constrictors in the ductsbetween the place at which the mist is formed and the member or membersto be lubricated. The oil mist is precipitated at the constrictors andchanged to a mixture of fluid oil and air, whereby practically the wholeof the oil in the mist is utilized for lubricating purposes, which isnot the case as long as the oil is in the form of small particlessuspended in the air. The original transformation of the oil into oilmist then only serves the purpose of making it possible to transportvery small quantities of lubricant to the various members to belubricated, and to distribute the lubricant as desired.

The invention is illustrated in the accompanying drawings, in which Fig.1 shows diagrammatically a lubricating system;

Figs. 2 and 3 show two different forms of precipitating nipples;

Fig. 4 shows a precipitating nipple, combined with a sight glass; and

Fig. 5 shows a nipple combined with a filter;

Fig. 6 shows a precipitating nipple combined with a spray nozzle; and

Fig. 7 shows a nipple combined with a drip oiler.

Our improved method of lubrication may be practiced by using thelubricating system shown in Fig. 1, wherein the numeral 1 indicatesgenerally an oil mist lubricator of known design. to which air underpressure is supplied from a suitable source through an air line 2. Theoil mist generated in the lubricator passes into a main duct 2,959,249Patented Nov. 8, 1960 "ice 3, which is common to a number of ductsbranching otr' therefrom and each leading to a machine part to belubricated. Thus the duct 4 leads to a bearing housing 5, in which is abearing to be lubricated. Before reaching the housing 5 the oil mistfrom the duct 4 passes through a precipitating nipple 6. Theprecipitating nipple 6 and a spray nozzle 28 are connected to the duct7. The duct 8 leads to a precipitating nipple 6 and a drip oiler 35. Theduct 9 is provided not only with a precipitating nipple and drip oiler,as is the duct 8, but also with a sight glass assembly 17. A filter 20is connected in front of the precipitating nipple 6 in the duct 10. Thenipple 6 in the duct 11 is provided with a sight glass assembly 17. Theinternal diameter of the branch ducts leading to the precipitatingnipples may be about 6 mm., or somewhat greater if a larger quantity oflubricant is required. The internal diameter of the main duct should be12 mm. or more.

The precipitating nipple 6 is illustrated in Fig. 2. It is provided withtwo threaded portions 12 for connection to the lubricating system. Thenipple has an axially extending channel or bore 13, which is veryconstricted relative to the inside diameter of the remainder of thesystem. The diameter of the bore of the nipple chosen may vary,according to the quantity of lubricant to be provided, from about 0.7mm. to about 2.8 mm., but will usually be of the magnitude of about 1mm. The channel 13 opens into a wider cross channel 14. An arrow on thenipple indicates the direction of flow in which the precipitating effectof the nipple is greatest. It has been found that when the oil mistflows through the nipple in the direction indicated by the arrow, asmuch as 98% of the particles of oil in the mist can be precipitated toform fluid oil. In this manner it is possible to utilize practically thewhole of the oil in the oil mist for lubricating purposes.

In a typical system, the ratio of the cross-sectional areas of thebranch duct and nipple bore will therefore usually be in the order of36:1. The ratio of the main duct area to the nipple bore area willusually be in the order of 144:1. Even with several nipples, for example6 as shown in Fig. 1, the total ratio of the main duct area to nipplearea will be in the order of 24:1. It is an inherent characteristic ofany fluid flow system that the relative velocities of the fluid atdifferent positions will be inversely proportional to the relativecross-sectional areas at the positions. Hence, with the 24:1 ratio setforth above, the fluid in each nipple bore is approximately twenty-fourtimes as great as its velocity in the main duct.

- not efliciently precipitate the oil.

The precipitating-nipple is preferably connected in the branch ductleading from the main duct to the bearing 'to be lubricated. By means ofthe nipples it is possible to distribute the lubricant among the variousbranch ducts in proportions as required by the various bearings. This isdone by using for each bearing a nipple having a bore of suitablediameter. If it is found that a bearing requires more, or possibly less,lubricant the nipples can easily be exchanged.

Fig. 3 shows a form of the nipple which does not differ in principlefrom the nipple according to Fig. 2,

but which is very suitable for use when the oil mist is led throughchannels in a bearing housing instead of through tubes. This nipple isprovided with two axially extending channels 13, both of which open intothe cross channel 14.

Fig. 4 shows a precipitating nipple 6, combined with a sight glass 15,mounted in a housing comprising two parts 16 and 17 screwed together.The cylindrical glass 15 is sealed by packings 18.- The direction offlow is from the nipple and the oil and air leave through an openng 38.If the speed or the flow is sufficiently great, it is possible to seethrough the glass how the oil precipitated in the nipple follows thestream of air and thus check that no stoppage has taken place.

In the device according to Fig; 5, the nipple 6 is screwed into a body19 of a filter and holds a casing 20 an the body. The body 19 isprovided with an axially extending channel 21, which opens into a pairof cross ehannels 22. These lead to an annular chamber 23 between thecasing 20 and the body 19. A peripheral groove 24 is provided in thebody from which a pair of cross channels 25 lead to the axiall extendingchannel 13 in the nipple 6 through an axial "ore 26 in the body 19, Afilter 27 surrounds the groove 24 and separates it item the chamber 23.The oil mist flows through the bhannel 21 and the cross channels 22 tothe chamber 23. After passing through the filter 27, where it isfiltered, and into the groove 24, it proceeds further through the crosschannel 25 and the bore 26 to the channels 13 and 14 in the nipple,where precipitation takes place. In this manner any loose particles orsolid bodies are prevented from reaching the relatively constrictedpassage 13 where they might become lodged. As a rule the ducts will befree from such particles and the filter need only be used in especiallyimportant cases.

Fig. 6 shows a precipitating nipple 6 connected to a spray nozzle 28 bymeans of a sleeve 29. The nozzle has a pair of threaded portions 30 anda cylindrical extension 31. It has an axial bore 32. One end of theension 31 is wedge shaped so that a pair of sharp points 33 are formed.A protecting sleeve 34 for the points is screwed onto one of the threads30. The cross sectional area of the bore of the nozzle should be 50% to100% greater than that of the precipitating nipple. The oil precipitatedin the nipple gathers on the points 33 and is carried along by the flowof air in the form of small drops, which are spread onto the surface tobe lubricated. The nozzle is suitable for lubricating free surfaces suchas plates, tools for presses, gear teeth, drivlug chains, etc. Incertain cases, for instance for lubrieating bearings in bearinghousings, the nozzle can be mounted directly in a threaded hole in thewall of the housing so that it points toward the rolling bodies of thebearing.

For lubricating sliding surfaces, it is preferable to have an apparatuswhich can deliver drops of oil separate from the flow of air. Anapparatus of this kind is shown in Fig. 7, and consists of aprecipitating nipple connected to a drip oiler. The drip oiler has achamber 35, provided at its lower end with an oil outlet 36. At the topof the chamber are a number of air escape holes 37. A cover 38 isscrewed on to the chamber and has a downwardly directed flange 39 forprotecting the holes. While passing through the precipitating nipple 6the oil particles suspended in the oil mist are united to form fluidoil, which emerges from the chamber 35 through the outlet 36 in the formof drops of oil. The air escapes through the outlets 37. The apparatusthus functions as an oil dripper and the quantity of oil can beregulated by using a precipitating nipple having a suitable area offlow. When a machine is being started for the first time it may beadvisable to unscrew the cover 38 and drop a few drops of clean oil intothe chamber 35.

The oil dripper according to Fig. 7 can be combined with the sight glassaccording to Fig. 4, whereby it is possible to chcek the flow of the oilthrough the glass. In order to check if lubricant is reaching all partsto be lubricated, especially in cases where there is no sight glass, avalve (40 in Fig. 1) can be connected at any suitable point in the mainduct, whereby the duct can be put in communication with the atmosphere.It is thus possible to lower the pressure in the main duct whilemaintaining or even increasing the production of oil mist. The rate ofnow through the precipitating nipples can in this way be reduced to sucha low value that none, or only a very small part, of the oil mistflowing through the nipples is precipitated in the form of fluid oil.The oil mist reaching the various places of lubrication leaks outthrough the seals or' through the outlets from the branch lines and isvisible in the form of a white mist.

Other combinations of the elements above described are, of course,possible without departing from the spirit of the invention. The nipplescan be provided with any number of axial channels. It is also possibleto use filters or the like, which form a greater number of constrictedpassages than the nipples above described.

The word surface as used in the claims refers to the peripheral wall ofthe cross-channel 14 and any equivalent thereof.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent of the United States, is:

l.- The method of supplying lubricant to a machine having parts to belubricated, which parts are incapable of precipitating suflicient oilfrom an aerosol, said method comprising the steps of producing anaerosol characterized by very fine mist particles, conveying the aerosolto positions adjacent the parts to be lubricated, increasing thevelocity of the aerosol to a relatively high velocity in each position,maintaining substantial flow of high velocity aerosol, directing thehigh velocity aerosol against a stationary surface generally transverseto the direction of aerosol flow to precipitate substantially all of theoil from the aerosol, and conveying the precipitated oil in liquid formto the parts to be lubricated.

2. The method of supplying lubricant to a machine having parts to belubricated, which parts are incapable of precipitating suflicient oilfrom an aerosol, said method comprising the steps of producing anaerosol characterized by very fine mist particles, conveying the aerosolto positions adjacent the parts to be lubricated, increasing thevelocity of the aerosol to a relatively high velocity in each position,directing the high velocity aerosol against a stationary surfacegenerally transverse to the direction of aerosol flow to precipitatesubstantially all of the oil from the aerosol, and conveying theprecipitated oil in liquid form to the parts to be lubricated.

References Cited in the file of this patent UNITED STATES PATENTS

